Hi Harry,
Thank you for posting your query on Microsoft Community.
This issue could be caused due to incompatible device driver and even failure of power supply during any important process in operation or due to some issues with the disk drive. Normally, if you are unable to boot the Windows 8 to its Start Screen, the Automatic Repair will check for the errors which is preventing Windows from booting up and will fix it. If this does not happen, then when you may need to run the Automatic Repair by booting the computer to Windows 8.1 installation/recovery disc. It will fix the issue if the issue with any startup files required for Windows 8.1 to boot up.
If you do not have Windows 8.1 installation DVD, you will have to create one, boot the computer from it and then perform an Automatic Repair. To create installation media, you may refer to the article given below:
Create installation media for Windows 8.1
Having created the installation media, I would suggest you to try the following methods and check if the issue persists.
Method 1: Disconnect all the unnecessary external devices connected to the computer (except the mouse and the keyboard)
I would suggest you to disconnect all the unnecessary external devices connected to the computer and then check if you still face this issue. This is to check if the issue is caused by any of the external devices connected to the computer. If the issue persists, then go ahead with the next method.
Method 2: Perform an Automatic Repair of Windows 8 using the installation media.
a) Contact the computer manufacturer to change the boot order of the computer. You will have to change the boot device to CD/DVD or USB drive and then boot from the Windows 8 installation media.
b) In the “Windows Setup” dialog box that appears, set the Time and currency format, Keyboard or input method and the language to install and then click “Next”.
c) Click on “Repair your computer” from the lower left corner.
d) From the “Choose an option screen”, click on “Troubleshoot”.
e) Click “Advanced Options” in the “Troubleshoot” screen.
f) In the “Advanced Options” screen, click “Automatic Repair”.
g) Follow the on-screen instructions to complete the Automatic Repair.
Hope this information helps. Please let us know if you need any other assistance with Windows in future. We will be happy to assist you.